This invention relates generally to manually-operable, multidirectional control devices and more specifically to electrical joystick controls for controlling spatial variables in electrical apparatus such as video displays and the like.
Directional controllers, popularly known as "joysticks," are widely used for controlling a variety of electrical devices, such as video displays in electronic amusement and instructional machines requiring positional or directional control in two dimensions. Known joysticks typically employ an elongated handle or lever pivotally mounted on a base for angular movement relative to the base about a nominal vertical axis. Manipulation of the handle generates switch closures to transmit electrical control signals from the joystick corresponding to the direction of movement of the handle. Because such control devices typically utilize pressure switches and springs to restore the handle to a vertical position, a certain amount of force is required to manipulate the handle. Continuing use of these controls over an extended period of time tends to fatigue the users.
In an attempt at correcting this disadvantage, Aamoth, et al. proposed, in U.S. Pat. No. 4,124,787, an improved joystick control mechanism. Their design sought to reduce the force needed to activate the switches and thereby minimize user fatigue. However, it failed to solve these problems. With the explosive growth of video display games, many of which are operated by joysticks similar to the Aamoth, et al. design, a previously unknown wrist disability has become so commonplace that it has acquired a nickname--Space Invaders Wrist.
Several features of the Aamoth, et al. design and other prior control mechanisms are disadvantageous and some are believed to contribute to the aforementioned wrist disability. One such feature is that the handle is pivoted relative to a fixed base. The disadvantage is that the user must employ two hands, one to hold down the base and the other to manipulate the handle. Another disadvantage is that the handle must be manipulated in an unnatural manner. More specifically, it must be pivoted about a pivot point within the base, whereas the normal pivoting action of a person's fist is about the wrist and forearm. A further disadvantage arises from the use of restorative springs and pressure switches which necessitate the application of a certain amount of force to pivot the joystick sufficiently to actuate the switches. It would be preferable to have a multidirectional controller which avoids these disadvantages.
Besides the aformentioned pressure switches, several types of switches are known which are actuated in response to position or movement. U.S. Pat. No. 3,935,669 to Potrzuski, et al. discloses a switch mechanism which is actuated in response to centrifugal force due to rotation about any of three axes. U.S. Pat. Nos. 3,787,647 to Hughes and U.S. Pat. No. 4,201,900 to Marchev disclose fluid-type gravity switches of various configurations. However, none of these devices are known to have been used for electrically controlling multidirectional variables. More specifically, these patents do not disclose a joystick or similar electrical control apparatus for controlling movement or position of images in an X-Y plane on a video display. Nor do they disclose gravity switches arranged to control movement or position of a variable in both positive and negative directions along a single axis. Similarly, they do not disclose switches capable of controlling signal magnitude as well as direction.
Accordingly, there remains a need for a multidirectional control device for controlling spatial variables in an electrical apparatus, such as the X-Y control circuits of a video display device, without the disadvantages of prior joystick control mechanisms.